Various esters of citric acid are known and have been used as plasticizers for various polymeric materials as described, for example, in PCT Patent Application Publications WO 2011/082052 (Myers et al.), U.S. Patent Application Publication 2011/0046283 (Grass et al.), and U.S. Pat. No. 4,710,532 (Hull et al.), U.S. Pat. No. 5,026,347 (Patel), U.S. Pat. No. 6,403,825 (Frappier et al.), U.S. Pat. No. 5,102,926 (Ross et al.) and U.S. Pat. No. 7,166,654 (Fujita et al.). These esters are typically prepared from citric acid and petroleum based alcohols.